Studies On The Synthesis,Structure And Photo-Luminescence Properties Of Novel Organic Luminescence Rare Earth Complexes

In order to design excellent photo and electro-luminescent Lanthanide complexes. Five new oxadiazole- functionalized amide ligands L₁, L₂, L₃, L₄ and L5 ,and one novel oxadiazole-functionalized β -diketone ligand (L₁₀)have been synthesized ,which can be used as the first ligands for Europium complexes ,meanwhile ,nine 1,10-phenanthroline derivatives of neutral ligands were prepared .All those compounds were characterized by IR,UV and 1HNMR spectrum, the chemical structures of the compounds were shown as follow.With L₁, L₂, L₃, L₄ and L5 as the first ligand, TPPO, N₁, N₂, dpq and dpmq as the second ligang ,twenty five novel europium complexes have been prepared and characterized by IR, UV and photoluminescent spectrum the relative solid state luminescent intensities quantum efficiencies and radiation lifetime of Eu³⁺ excited state ⁵D₁were determined ,the triplet state energy level of the first ligand L₁, L₂, L₃, L₄, L₅ were obtained by measuring the phosphorus spectrum of Gadolinium complexes with the first ligands. The relationship between the relative luminescent intensities and quantum efficiency and the triple state energy of the first ligands were also investigated the experimental results show that the Europium complex with TPPO as the neutral ligands with relative low quantum efficiencies ,compare with other series of the complexes .But they all exhibit relative strong solid luminescent intensities owing to inconspicuous concentration quenching phenomena ,Furthermore the quantum efficiencies of the complexes in the series are in good accordance with the energy gap value between the triple state and the ⁵D₁ emission state of Eu³⁺ ion consisting with the established energy transfer theory .the other series of the complexes with N₁, N₂, dpq, dpmq as the neutral liangds all have relative high quantum efficient Photoluminescent properties .However, all those complexes show apparent luminescent concentration quenching phenomena in the solid state ,and as a result these complexes could only be used as efficient emitting materials as a dopant in a matrix in OLED devices.The crystal structure of three europium complexes Eu(DBM)₃N₄, Eu(L₁)₃N₁, Eu(L₃)₃(TPPO)(H₂O) have been determined by X-ray structure analysis .in complexes Eu(DBM)₃N₄, Eu(L₁)₃N₁ each Eu³⁺ ion is eight coordinated by the geometry ,in complex Eu(L₃)₃(TPPO)(H₂O), Eu³⁺ ion is also eight coordinated, but coordination geometry is di-caped trigonal prism.The domination of the ³D₀→⁷F₂ in those complexes is a typical feature that no inversion center is occupied by Eu³⁺ ion which is in good agreement with the structure analysis result.